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[TowerTalk] re: [towertalk] Another Stacking question

To: <towertalk@contesting.com>
Subject: [TowerTalk] re: [towertalk] Another Stacking question
From: chapoton@smtp-gw.gdls.com (Henry G Chapoton)
Date: Thu, 23 Jul 1998 10:58:01 -0400
     Don:
     
     Odd 1/4 wave multiples force equal currents in the antennas, which 
     helps preserve the desired phasing and reduce pattern degradation.  
     This is true whether you use 75 ohm for matching or have a 50 ohm 
     system with a Stackmatch.  A good reference is Llewellen in the ARRL 
     Antenna book regarding feeding arrays of verticals.  In a yagi stack, 
     the problem is generally not as severe as in his examples given the 
     increased (in terms of wavelength) spacings and therefore reduced 
     mutual coupling effects.  Another school of thought is equal multiples 
     of 1/2 wave, which repeats the antenna's impedence and eliminates 
     transformtion effects.  An antenna with a relatively flat impedence 
     bandwidth would probably make for a more forgiving system whichever 
     method you use.
     
     I never found cutting coax to an electrical length to be unmanageable. 
      This isn't rocket science and the tolerances required for an 
     effective system aren't that tight.
     
     
     Greg
     na8v/4
     
     You wrote:
     
To: <towertalk@contesting.com>
     Date: Wed, 22 Jul 1998 16:11:04 -0600 (MDT)
     From: Don Moman <ve6jy@freenet.edmonton.ab.ca>
     Subject: [TowerTalk] Another Stacking question
     
     I see comments on two methods of connecting antennas in a stack.
     Most frequently, using equal lengths of cable from all antennas is
     mentioned.  The other way mentioned is using odd multiples of 1/4 wave
     lengths of 50 ohm. 
     (a lot snipped)
     
     .  I am willing to believe both methods are fine, and perhaps the
     equal length approach is simpler (no math) and that is why it is 
     suggested
     more frequently. Is one method better than the other? and why? 
     (snip)
     
     Thanks, 73
     Don
     VE6JY

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